1. Field of the Invention
The present invention relates generally to the operation of coke ovens and more particularly to an improved dust collecting system for a coke oven.
2. Description of the Prior Art
In the operation of coke ovens, a severe problem of dust being thrown off has been caused at the step of discharging coke from a coke oven, hereinafter being referred to as the coke discharge step, and at the step of charging coal for carbonization, hereinafter being referred to as the coal charge step.
In order heretofore to collect such gases and dust given off from a fire extinguishing, or quenching, car and a coke guide car at the coke discharge step, a system of drawing or sucking dust and gases through a fixed duct to a dust collector, or settling chamber, disposed on the ground has been employed which features covering the coke guide car with a hood. This system is effective and has been relatively satisfactory.
However, the gas spouted out from the carbonizing, or oven, chamber at the coal charge step contains dust and a large content of combustible gases and tar mists. Accordingly, though various dust collecting systems have been proposed, a desirable system which is fully satisfactory from the viewpoints of stability, economy and efficiency of dust collection has yet to be attained. For example, it has been proposed to employ a system wherein a combustion chamber and a gas sucking device are equipped on the coal feed car so as to provide for suction and combustion of gas spouted from the oven chamber and to feed the exhaust gas through a fixed duct to a dust collector disposed on the ground. It has been also proposed to employ such a system having a combustion chamber disposed on the ground.
The dust containing gases which spout out at the coal charge step have low calorie value and are of large volume. In order to attain a complete combustion, it is necessary to increase the temperature in the combustion chamber to higher than 700.degree. C. Accordingly, a large amount of auxiliary fuel is required, thus making for an uneconomical operation.
In the conventional combustion system, only the ignition source is fed into the combustion chamber, so as to provide for combustion of only the self-combustible components in the dust containing gases. Accordingly, the exhaust gas, which contains unreacted gases and tar mists, is fed into the dust collector disposed on the ground. It has been proposed to employ a system having no combustion chamber, wherein the dust containing gases are sucked from the coal feed car through a fixed duct to a dust collector disposed on the ground. In the latter system, a large amount of combustible gases and tar mists are directly fed into the dust collector. Heretofore, a mechanical wet type dust collector has been employed as the dust collector at the coal discharge step because it contains such combustible gases and tar mists. It has been difficult to employ an electrical dust collector cause of the expense and because of th danger, as combustible gases are involved. However, the efficiency of dust collection of dusts having less than 1.mu. of diameter and tar mists is quite low in the wet type dust collectors, and the dusts and tar mists are passed through the dust collector to be discharged into the atmosphere as floating dusts whereby pollution of the environment is caused over a broad area.